The present invention relates generally to a method of determining a sensitivity of a biosensor arrangement, and a biosensor sensitivity determining system.
Field-effect semiconductor devices can serve as a basis for chemical and biological sensors. In such a sensor, the presence of chemical or biological substances changes the conductance of the field-effect semiconductor device. Thus, the amount of change of conductance reflects the amount of chemical or biological substances put onto the sensor.
For example, a planar field effect transistor (FET) can be configured as a chemical or biological sensor by modifying the gate dielectric (on which no gate electrode is present) with molecular receptors or a selective membrane for the analyte of interest. The binding of a charged species to the molecular receptors then results in depletion or accumulation of carriers within the transistor structure, see for example document “P. Bergveld, IEEE Trans. Biomed. Eng., vol. BME-19, p. 342, 1972”.
Different ways of calibrating such a sensor are known. For example, in document “M. Abe, K. Murata, T. Ataka, K. Matsumoto, Nanotechnology, vol. 19, 2008”, a calibration technique is presented in which a set of test solutions having different concentrations of target species is used to construct normalized characteristic curves for the sensor. This approach might be useful for certain applications such as pH and ion concentration measurement that detects reversible process. However, it cannot be used for detection of antibody-antigen binding process, for example, which is practically irreversible due to the extremely small dissociation constant of the process. Moreover, considering that a whole set of test solutions has to be prepared for calibration curve construction and the calibration should be performed for every single biosensor chip, this method is expensive and not suitable for point-of-care applications where the cost effectiveness is very important.
It would be desirable to provide a calibration method of chemical or biological sensors which is applicable to both reversible and irreversible processes and only needs minimal effort to be carried out.